Item specifics
Description
Product Overview
The pH test module kit includes a pH measurement circuit board and a pH combination electrode probe, capable of accurately measuring 0-14pH with analog voltage output, compatible with Arduino and other microcontrollers. The module operates at 5V with a response time ≤5 seconds. The probe measures 0-60℃ aqueous solutions with a BNC connector for plug-and-play use. Three configurations are available: module only, module + non-refillable probe, and module + refillable probe. Non-refillable probes contain gel KCl for easy maintenance; refillable probes can be topped up with KCl solution for long-term continuous use. Ideal for aquariums, hydroponics, laboratories, and water quality monitoring.
Core Features
Measurement Range： pH 0-14, full-range acid-base detection
Analog Voltage Output： Module outputs analog signal directly readable by MCU ADC pins
Wide Power Supply： 5±0.2V DC, operating current 5-10mA, power ≤0.5W
Fast Response： Response time ≤5 seconds, settling time ≤60 seconds
BNC Standard Connector： Probe uses BNC connector, compatible with most pH meters and controllers
Probe Operating Temperature： 0-60℃ (module -10~50℃), suitable for regular aqueous solutions
Refillable/Non-Refillable Options： Non-refillable with gel KCl (easy maintenance); refillable for long-term continuous use
Module Dimensions： 42×32×20mm with 4 M3 mounting holes
Electrode Maintenance Tips： Activate before use, clean regularly to maintain accuracy
Applications
Aquarium water quality monitoring (pH), hydroponic nutrient pH adjustment, laboratory experiments, industrial wastewater monitoring, drinking water testing, soil pH measurement (with pre-treatment), teaching demonstrations and DIY projects
Key Advantages
Full-Range Accurate Measurement： 0-14pH covers acidic, neutral, alkaline liquids with high precision
Plug-and-Play Easy Integration： Analog voltage output connects directly to Arduino, Raspberry Pi ADC pins – no extra drivers needed
Low Power Design： 5V supply, only 5-10mA current – ideal for battery-powered portable devices
Flexible Probe Options： BNC interface for quick probe replacement. Non-refillable for convenience, refillable for long-term monitoring
Fast Response, Stable Readings： ≤5 second response time, real-time pH changes with stable software-filtered readings
Complete Kit Ready to Use： Module + probe + instructions – build your pH monitoring system immediately
Why Choose QIXINWEI
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FAQ:
What is this pH test module and pH electrode probe? How does it work?
This kit consists of a glass‑bulb pH electrode probe (typically a combination electrode) and a signal conditioning board. The probe generates a tiny voltage (millivolts) proportional to the hydrogen‑ion activity in the solution — ideally 0 mV at pH 7 (neutral), about +414 mV at pH 0, and about −414 mV at pH 14 at 25 °C. The board amplifies and offsets this signal so that it can be read by a microcontroller’s analog‑to‑digital converter (ADC). The module outputs an analog voltage that is linearly related to pH, typically with a sensitivity of ~59.16 mV/pH at 25 °C.
How do I connect the pH module to an Arduino or ESP32?
Wiring is very simple. Connect VCC → 5 V (most boards require 5 V), GND → GND, and the analog output (often labelled Po or AO) → any analog input pin (e.g., A0 on Arduino Uno). For ESP32, be aware that its ADC input range is 0–3.3 V, while many pH boards output 0–5 V; you will need a voltage divider or level shifter on the signal line to avoid damaging the ESP32. In code, simply read the analog value with analogRead() and convert it to pH using a linear calibration formula.
How do I calibrate the pH sensor for accurate readings?
Calibration is essential. You need at least two standard buffer solutions — typically pH 4.01 (acidic) and pH 6.86 or 7.00 (neutral). A third point, pH 9.18, improves accuracy in the alkaline range. Rinse the probe with distilled water, place it in the first buffer, let the reading stabilize, and record the ADC value. Repeat for the second buffer. The relationship is linear, so you can use these two points to calculate a linear equation: pH = slope × ADC value + intercept. Most example code uses the map() function or simple two‑point math. Calibrate periodically, as probes age.
What is the typical analog output voltage range for pH 0–14?
After signal conditioning, the module typically outputs a voltage centered around 2.5 V at pH 7. The voltage increases for acidic solutions (lower pH → higher voltage, e.g., ~3.5 V at pH 4) and decreases for alkaline solutions (higher pH → lower voltage, e.g., ~1.5 V at pH 10). The exact range varies by board manufacturer, but the span is usually designed to fit within a 0–5 V microcontroller ADC range. Always check your specific module’s datasheet or measure it during calibration.
What is the difference between a pH electrode and a simple analog pH sensor module?
The pH electrode is the glass‑bulb probe itself, containing a reference electrode and a measurement electrode. It produces a millivolt signal that requires high‑impedance amplification. The pH module (signal conditioning board) provides this amplification, offset adjustment, and a BNC connector for the electrode. Many low‑cost modules use a simple op‑amp circuit (often with a potentiometer for offset adjustment). Higher‑quality modules include temperature compensation and better noise filtering. You must have both the probe and the module to read pH with a standard microcontroller.
How does temperature affect pH readings, and do I need temperature compensation?
The Nernst equation slope varies with temperature: at 25 °C it is 59.16 mV/pH, but at 0 °C it drops to about 54.2 mV/pH and at 100 °C it rises to about 74.0 mV/pH. Most basic modules do not include automatic temperature compensation (ATC). For precise work, you should measure the solution temperature with a separate sensor (e.g., DS18B20) and apply a software correction using the Nernst equation. For hobbyist applications measuring near room temperature, the error is small and often acceptable without compensation.
How should I store and maintain the pH electrode probe?
The glass bulb must never dry out. Always store the probe with the tip immersed in storage solution (often 3M KCl) or, in a pinch, in pH 4 buffer solution. Do not store in distilled water, as it leaches ions from the glass bulb and reference junction, destroying the probe. Before and after use, rinse the probe with distilled or deionized water and gently blot dry with a lint‑free tissue (do not rub). If the probe response becomes sluggish, soak it in cleaning solution or gently refresh the reference electrode by replacing the filling solution, if the probe allows it.
What is the typical accuracy and resolution of this pH sensor?
With careful calibration, most hobbyist pH modules can achieve an accuracy of about ±0.1 pH at room temperature, which is sufficient for aquaponics, hydroponics, pool monitoring, and science projects. The 10‑bit ADC of an Arduino Uno gives a theoretical resolution of about 0.014 pH per bit (over the full 0–14 range), but noise in the system usually limits the practical resolution to around 0.05 pH – 0.1 pH. Using a 12‑bit ADC (e.g., on an ESP32 or external ADS1115) improves the noise‑free resolution significantly.
Can I submerge the entire pH module in water?
No. Only the pH electrode probe (the glass bulb and the lower plastic shaft) is designed to be immersed in liquid. The BNC connector, the signal conditioning board, and all wiring are not waterproof and must be kept dry. If you need to monitor a remote liquid, mount the board in a sealed enclosure and run only the electrode cable out through a waterproof gland. Immersing the board will destroy it immediately.
What are the most typical applications for this pH sensor module?
It is widely used in aquaponics and hydroponics to maintain optimal nutrient solution pH, fish tanks and aquarium monitoring, swimming pool and spa water quality control, environmental water testing, school chemistry and STEM experiments, and fermentation monitoring (e.g., kombucha, beer brewing). The analog output makes it easy to integrate into any microcontroller‑based data logging or automatic dosing system.